Evaluation of Frame loss Rate of MPEG.4 video transmission over 802.11 e in MANETs.
Dr.Swati Sharma a,Amarjeet Thind and Nipun Sharma
aUniversal Group of Institutions, Lalru, Mohali.
Email id:
Abstract
Frame loss rate is a very important parameter in determining the Quality of service of video transmission. This paper presents efficient mechanism for delay sensitive transmission of video over IEEE 802.11 e. We use here NS2 simulator for simulation. And different routing protocols are analyzed by different mapping techniques like 802.11 e EDCA, static mapping and dynamic mapping.
Keywords: MANETs, Frame loss rate, mapping, routing protocols, EDCA.
INTRODUCTION
MANET is a collection of mobile nodes without the required intervention of any centralized access point. It is a temporarily formed network which is created, operated and managed by nodes themselves. IEEE 802.11e-2005 or 802.11e is an approved amendment to the IEEE 802.11 standard that defines a set of Quality of Service enhancements for wireless LAN applications through modifications to the Media Access Control (MAC) layer. 802.11 is an IEEE standard that allows devices such as laptop computers or cellular phones to join a wireless LAN widely used in the home, office and some commercial establishments.
To support the varying Quality-of-Service (QoS) requirements of emerging applications, a new standard IEEE 802.11e [1] has been specified. The 802.11e standard defines four access categories (ACs) that have different transmission priorities. The transmission priority is the probability of successfully earning the chance to transmit when individual ACs are competing to access the wireless channel; the higher the transmission priority, the better is the opportunity to transmit. However, for a wireless channel, the unavoidable burst loss, excessive delays, and limited bandwidth become challenges for efficient multimedia transmission over wireless network. Consequently, several advanced mechanisms were proposed based on 802.11e to support multimedia transmissions and in particular video transmission quality. Most of the proposed mechanisms improved the performance by adjusting the operation of 802.11e MAC, such as Contention Window size, TXOPlimit and data transmission rate. However, the MANETs present many challenges, especially when real-time traffic must be supported in terms of providing Quality of Service (QoS) guarantees. Providing QoS for real-time traffic over IP-based networks is still an open issue because existing active queue management schemes have been designed for TCP-compatible traffic. MANETs present the worst-case scenario for QoS guarantees due to their distinct characteristics, such as contention from multiple users (when using 802.11) and limited bandwidth.
MPEG-4 (Motion Pictures Expert Group-4) standard was introduced in late 1998. This standard enables the compression of audio-visual data. Initially this standard was concerned with a similar range of applications to those of H.263, each running over very low bit rate channels ranging from 4.8 to 64 Kbps. Later its scope was expanded over the internet and various types of networks [2]. The MPEG-4 standard is used in relation to audio and video with interactive multimedia applications over the internet. The compression process in MPEG-4 standard is different from MPEG-1 and MPEG-2.
MPEG-4 compresses the video in the range from 5Kbps to10Mbps. This standard comprises many features in which user not only to access a complete video but also can access the individual elements that make up each scene within the video [38]. The encoding algorithm- ACE (Advanced Coding Efficiency) used in this standard, MPEG-4 provides highest efficiency during encoding [41]. In MPEG-4 the frames are divided into three categories. I,P and B frames. In this paper we have calculated all the individual losses of I P and B frames as the importance and priority of the frames is different.
The three mapping techniques that we have compared for the evaluation of Frame Loss (I,P and B) frames are IEEE 802.11e EDCA, Static Mapping and Dynamic Mapping.
Simulation Setup and Results
To evaluate the performance of our proposed cross-layer mapping algorithm, we have conducted simulations using a widely adopted network simulator NS-2, and integrated with EvalVid. The results of the proposed mapping algorithm are compared with the results derived from IEEE 802.11e EDCA and the static mapping algorithm. The video source used in the simulation is YUV QCIF (176 x 144), Foreman. Each video frame was fragmented into packets before transmission, and the maximum transmission packet size over the simulated network is 1000 bytes. There are eight ad-hoc wireless nodes where one is video server and another is the video receiver. The data rate of the wireless link is 1Mbps.
NS-2 Simulator (Network Simulator) NS-2 is a discrete event simulator targeted at networking research. In wired and wireless (local and satellite) networks NS-2 provides substantial support for simulation of TCP, routing, and multicast protocols. NS-2 began as a variant of the REAL network simulator in 1989 and has evolved substantially over the past few years. In 1995, NS-2 development was supported by DARPA through the VINT project at LBL, Xerox PARC and UCB but in recent years NS-2 development is supported through DARPA with SAMAN [50] NS-2 is an object oriented simulator which is written in C++, having an OTcl interpreter. The simulator supports a two hierarchies which are closely related to each other in which one class of hierarchy in C++ (also called the compiled hierarchy) and a similar class of hierarchy within the OTcl interpreter (also called the interpreted hierarchy).
Calculation of Frame loss
We have calculated the frame loss (comprehensive analysis of frame loss i.e I,P and B frames) of MPEG 4 traffic for various routing protocols for both heavy and light loads. Furthermore we have treated all the mapping techniques viz 802.11 e EDCA , static mapping and dynamic mapping to see the performance of the network for least frame loss at the receiving end.
Calculation of frame for HEAVY LOAD
a) 802.11 EDCA
Traffic 0 1 4 2 2RP / FRAME LOST
TOTAL LOST / I / P / B
AODV / 91 / 18 / 19 / 54
DSR / 92 / 17 / 20 / 55
DSDV / 89 / 21 / 18 / 50
b) Static mapping
Traffic 1 1 4 2 2RP / FRAME LOST
TOTAL LOST / I / P / B
AODV / 181 / 34 / 36 / 111
DSR / 178 / 34 / 36 / 108
DSDV / 188 / 35 / 37 / 116
c) Dynamic mapping
Traffic 2 1 4 2 2RP / FRAME LOST
TOTAL LOST / I / P / B
AODV / 134 / 31 / 29 / 74
DSR / 146 / 33 / 30 / 83
DSDV / 135 / 32 / 27 / 76
Results for heavy load:
The experimental results show that in case of lighter load i.e. when four video channel is propagated in between networks the frame loss is higher which is very natural and obvious.
Among light loads we find lowest frame loss(best performance) in 802.11 EDCA followed by dynamic mapping and static mapping results in the worst performance. However static mapping yield the worst results with large number of frames( I,B and P) loss. Among the routing protocols AODV and DSDV perform best and equal.DSR perform worst in all the mappings except static mapping.
Calculation of frame loss for LIGHTER LOAD
a) for 802.11 EDCA
Traffic 0 7 1 2 2RP / FRAME LOST
TOTAL LOST / I / P / B
AODV / 12 / 2 / 3 / 7
DSR / 11 / 1 / 3 / 5
DSDV / 12 / 2 / 3 / 7
b) for static mapping
Traffic 1 7 1 2 2RP / FRAME LOST
TOTAL LOST / I / P / B
AODV / 159 / 35 / 33 / 91
DSR / 159 / 35 / 33 / 91
DSDV / 159 / 35 / 33 / 91
c) for dynamic mapping
Traffic 2 7 1 2 2RP / FRAME LOST
TOTAL LOST / I / P / B
AODV / 0 / 0 / 0 / 0
DSR / 4 / 0 / 1 / 3
DSDV / 0 / 0 / 0 / 0
Results for lighter load:
The experimental results show that in case of lighter load i.e. when only one video channel is propagated in between networks the frame loss is too low which is very natural and obvious.
Among light loads we find lowest frame loss (best performance) in dynamic mapping, followed by 802.11 EDCA in static mapping results in the worst performance. However static mapping yield the worst results with large number of frames (I, B and P) loss. Among the routing protocols AODV and DSDV perform best and equal. DSR perform worst in all the mappings except static mapping.
Conclusion
We have calculated the Frame loss rate of MPEG 4 traffic for various routing protocols for both heavy and light loads. Furthermore we have treated all the mapping techniques viz 802.11 e EDCA , static mapping and dynamic mapping to see the performance of the network for the least Frame loss rate at the receiving end.
References
1. IEEE Std 802.11e-2005;"Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specifications Amendment 8: Medium Access Control (MAC) Quality of Service Enhancements", November 2005
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